Alternating current plunger type solenoid



'Jan, 15, 1952 Filed llay 11, 1946 R. s. OLSON ALTERNATING CURRENT PLUNGER TYPE SOLENOID 3 Shuts-Sheet 1 Jan. 15, 1952 OLSON 2,582,351

ALTERNATING CURRENT PLUNGER TYPE SOLENOID Filed May 11, 1.946 3 Sheets-Sheet 2 fi G. 056072,

Jan. 15, 1952 R. s. OLSON ALTERNATING PLUNGER TYPE SOLENOID 3 Sheets-Sheet 3 Filed May 11, 1946 7206/? 02 361% 61 OZSOJZ jy/ w Patented Jan. 15, 1952 ALTERNATING CURRENT PLUNGER. TYPE SOLENOID Bay G. Olson, Glenview, 11].,

allignor to The vox Company, Fort Wayne, 1nd,, a corl ration of Delaware Application May 11, 1946, Serial No. 869,050 3 Claims. 175438) The present invention relates to solenoids and to a novel method for manufacimring solenoids and, while'the novel product and process herein disclosed are not limited to the field of alternating-current solenoids, they are of particular utility in that connection.

Prior art methods for manufacturing solenoid frames involve expensive, wasteful and timeconsuming operations in punching out individual c-shaped laminations, in stacking the laminations to form a frame, and in driving rivets or other fastening means through the stacked laminations in order to secure them in a unitary assembly and to provide a mounting for the plunger. It is desirable toeliminate theresultant high cost factors involved in such operations.

Conventional solenoid frames consist of a great number of parts including separate laminations, rivets, outer plates and the like. It is highly desirable that this number be minimized.

It is an object of my invention to provide a solenoid which is extremely simple and inexpensive to fabricate and assemble, which involves a minimum number of parts and which avoids the limitations and disadvantages of prior-art devices.

Conventional solenoid frame fabrication requires the building up of a stack of laminations to a critical specified thickness. This is accomplished by a combination of the following delicate and expensive manufacturing operations: l irst, selective stacking of laminations of several different thicknesses (for example, 0.015, 0.025 and 0.031 inch) in order to diversify commercial tolerance errors and to balance excesses against deficiencies in thickness, and second, riveting the stacks under compression at various places. The disadvantages of this practice and the resulting product are: (1) increased cost arising from the procurement of materials of different thicknesses; (2) multiplication of the waste involved in punching operations; (3) undesirable operating characteristics caused by non-uniformity of compression of the several riveted sections; (4) misalignment of laminations and aggravation of such non-uniformity caused by rough treatment of the frame in manufacturing and operation.

In spite of these disadvantages, this total thickness is critical in the prior-art and has been accepted as such in developing the art. This fact is demonstrated by the conventional stacked frame disclosed in U. 8. Patent No. 2,311,432 to D. W. Davis, issued February 16, 1943. The reason is that the stack thickness controls the spacingoftheplungergmdeplatesinsucha manner that, for a given spacing between plates, a fixed stack thickness is required. In other words, the thickness of the stack has heretofore been treated as a mathematical function of the width of the plunger, since that width is determinative of the distance between the guide plates. A corollary of this accepted thesis in frame construction is the .driving of rivets through the flat sides of the laminations and the presentation of the thin edges of the laminations to the winding. This functional relationship between plunger thickness and stack thickness, for a given suide construction, is peculiar to solenoid construction and has heretofore characterized only those phases of the electromagnetic arts wherein guided plungers are involved.

It is desirable to avoid this functional relationship and all of its undesirable consequences and to provide a solenoid frame in which the frame .dimension corresponding to the conven-' tlonal stack width is independent of guide or plunger width. I solve this problem by departing radically from the prior art wherein this problem is presented, by winding a continuous strip of one thickness under uniform tension to make a frame, welding the frame to secure an integral structure, and presenting the flat sides of the strip to the winding. contrary to the accepted doctrines of the solenoid art.

It is also an object of my invention to provide a method for manufacturing solenoids, which method involves no stacking or riveting operations.

The above and other advantages and capabilities of my invention will be apparent from a detailed description of the accompanying drawings in which I have illustrated two preferred forms of my invention, but the construction therein shown is to be understood as illustrative and not as defining the limits of my invention.

In the accompanying drawings:

Fig. 1 is a perspective view of a preferred form of solenoid in accordance with my invention, showing the same completely assembled and with the plunger in one of the positions assumed in operation when the winding is not electrically energized;

Fig. 2 is a perspective view of the magnetic frame, showing the centering plate welded in place; i

Fig. 3 is a perspective view, partly broken away, of the guide member showing its relationships to the winding and its upturned portions for preventing complete withdrawal of the plunger from the frame during normal operation;

Fig. 6 is a longitudinal sectional view of the showing clearly the relationparts, the plunger being Fig. 1 embodiment, ships between the various in an on position;

Figs. 7, 8, and 9 are in section. taken along respectively, of Fig. 6, and tion of the arrows;

Fig. 10 is a front elevational sectional view, taken on a central plane passed through the frame and plunger (line lO-IO, Fig. 12). of a modified form of solenoid in accordance with the invention;

Fig. 11 comprises perspective views of the U-shaped locking member and the subassembly of plunger and guide member included in the Fig. 10 embodiment; and

Fig. 12 isa side elevational sectional view taken along line l2--l2 of Fig. 10 and looking in the direction of the arrows, showing the relationship between frame, coil, guide member, locking member and plunger.

Referring now specifically to Figs. 1 through 9, there is shown-a solenoid II in accordance with my invention. The process of manufacturing this solenoid is extremely simple. The laminated magnetic frame l2 consists of a single strip of magnetic steel of suitable grade for a desired application, continuously wound on a mandrel to the correct frame size, and formed mechanically views, in section or partly lines 1-1, 3-8, and -3,

looking in the directo properly set radius or tack welded to hold form. Although my invention is not limited to specific parameters, I have shown in my preferred embodiment nine turns of the strip. A suitable thickness of the strip is 0.025 inch. This is an advantageous construction. Each successive lamination is tightly wound on the previous adjacent lamination and each successive cross-section of the strip is radially displaced from the preceding one.

After the frame is wound to the desired specification, it can then be securely fastened together by spot or resistance welding not only at the free ends of the strip but also throughout the entire section at various points, or a set can be obtained by pressing. Thus the layers are secured in proper positions and alternating-current hum is minimized.

The frame is then placed in a horn die and a radial aperture I3 is pierced through one side of the frame in a single operation in order to permit the entry of a plunger I4 and a plunger guide member 15. After piercing aperture II. a centering plate It is welded to the frame opposite the aperture. This plate may be omitted for certain applications. This plate is normally made of steel. I

An exciting winding I1 is mounted within the frame and coupled to a suitable source of electric energy (not shown). This winding is wound on a bobbin [8.

Disposed in and projecting-through the aperture is the guide member 15, made of a suitable nonmagnetic material, such as brass. Means adapted to be placed radially inwardly of the frame for securing the guide member in the frame is provided in the form of laterally biased spring projections l9 and 20, integral with and cut out of the guide member. These spring projections constitute snap-action means on the guide member which cooperate with the frame in securin the guide member within the frame after assembly. The coil is inserted into the frame throu h the side opening, and then the plunger H and guide member ii are pressed into position. when the projections i9 and 20 clear the walls of aperture I3, they snap outwardly into. position, thereby locking the assembly of coil. frame and guide member together.

The plunger l4, formed of suitable magnetic material. is slidably movable within the guide member. Complete withdrawal of the plunger from the guide member during normal operation is prevented by the upstanding lugs 2| and 22, integral with the guide member, as best shown in Fig. 3. These lugs ride in slots 23 and 24, cut into the lower side of the plunger, as clearly shown in Figs. 6, 8, and 9. The guide member not only secures the coil H in place, but it also guides the plunger l4 and restrains it from complete withdrawal. A copper shading coil 25 is partially embedded in slots cut into the face of the plunger (Fig. '7). When the solenoid winding is energized. the plunger so moves that this face abuts against the centering plate ll or side of the case if the plate is omitted. This centering plate is closely embraced bythe sides, bottom, and flanged portions 29 and 30 of guide member I5, thus securing the guide member against lateral movement and providing a stable path of motion for the plunger.

The plunger is generally conventional and is provided with the usual extended laminations 3i and 32, forming a yoke adapted to be secured to whatever device is controlled by the solenoid, depending on the particular application.

The margins of the top side of the plunger are slightly undercut as shown at 33 and 34 so that flanged portions '29 and 30 slide in these marginal portions, the top sides of the flanged portions being substantially flush with that top side. The flanged portions do not extend the whole length of the guide member but terminate at 35 and 38. When the subassembly of guide plate and plunger is removed from the frame, the plunger can easily be removed from the guide member, since margins 33 and 34 clear flanges 25 and 30 when the plunger is pulled out of the guide, permitting withdrawal of lugs 2| and 22 from slots 23 and 24. Conversely. the plunger is readily inserted in the guide member and the subassembly of guide and plunger is placed in the frame with facility. The frame may be secured to a suitable base 36 by welding, as at 31.

The outstanding feature of this particular construction is that the entire fabrication and assembly are accomplished without the use of stacked frames and rivets, whereby considerable expense in production is saved.

In Figs. 10, 11, and 12 there is shown a modified form of solenoid which is generally similar to the form just described. Those elements in the Fig. 10 embodiment which are identical in construction and operation with elements of the Fig. 1 embodiment bear the same reference numerals, and similar elements bear the same reference numerals primed. The essential differences between the Fig. 1 and the Fig. 8 embodiments reside in the substitution of a spring biased U-shaped locking member 38 for the spring portions l9 and 20 and the upstanding lugs 2| and 22 of the guide member. The legs 39 and 40 of this locking member straddle a spring portion M of the guide member and this spring portion normally maintains the U-shaped member in such a position that the top of the closed U is slightly higher than the top of the guide member. The terminals of the legs ride in slots 23 and 24 formed in the plunger H. The plunger is formed with a depression 43. The plunger is initially so placed in the guide member that this depression is vertically aligned with the U-shaped member 38; this alignment is maintained while the subassembly of U-shaped locking member, guide member and plunger is pressed through aperture I3 into the frame. When the U-shaped member 38 clears the top wall of aperture I3, spring portion 4| springs outwardly, carrying with it the locking member, and restores the locking member to a position at which its closed portion is slightly above the top of the guide member. Further radial outward movement is prevented by the spool l8 of winding H, the closed end of the U-shaped member then being held between the spring portion ll and the spool. The side of the U-shaped member abuts the wall of frame I: and prevents withdrawal of the guide member from the frame (Fig. 10). The leg portions 39 and 40, riding in slots 23 and 24, prevent complete withdrawal of the plunger from the frame during normal operation.

Another important feature of my invention resides in the ease with which the solenoid may be disassembled. To disassemble the Fig. 1 embodiment, the spring portions I9 and are depressed. the guide member is withdrawn from the frame, the coil is taken out and the plunger is removed from the guide member. Disassembly of the Fig. 10 embodiment is readily effected by aligning the depression 43 with the U-shaped member 30, depressing that member and withdrawing the subassembly of guide member and plunger from the frame, whereupon the coil may be removed from the frame and the plunger may be removed from the guide member.

Thus it will be seen that the invention provides a solenoid which is extremely simple in construction, which has a minimum of parts and which may easily be fabricated by unskilled labor and rapidly put into mass production.

While there have been shown and described what are at present considered to be thepreferred embodiments of the present invention, it will be obvious to those skilled in the art that various modifications and substitutions of equivalents may be made without departing from the teachings of the invention and the proper scope thereof and it is accordingly intended in the appended claims to cover all such changes and modifications as fall within the true scope of the invention and outside of the scope of the prior art.

Having thus described my invention, I claim:

1. In a solenoid of the plunger type, a laminated open magnetic frame comprising a continuous strip of magnetic material, each successive lamination being tightly wound on the previous adjacent lamination and each successive cross-section of said continuous strip being radially displaced from the preceding one, said frame being formed with a radial plunger aperture, a plunger-guide member disposed in and projecting through said aperture, and an exciting winding around said guide member and latch means on said guide member positioned wholly within the winding-receiving opening in said frame and engaging said frame for securing said guide member therewithin.

2. A solenoid comprising a magnetic frame having an aperture formed in one side thereof, a guide member in said aperture, means integral with said guide member for securing it within said frame and in said aperture, a magnetic plunger slidably movable within said guide member, and means integral with said guide member for preventing withdrawal of said plunger from said frame during normal operation of said solenoid, the first-named means being releasable to permit withdrawal from said frame of both said guide member and said plunger.

3. A solenoid comprising a frame of magnetic material open to receive an exciting winding and formed with a radial aperture through a side thereof, a guide member projecting through said aperture, an exciting winding surrounding said guide member, a plunger longitudinally shiftable within said guide member, internal lugs carried by the guide member and engaging the plunger to limit the longitudinal movement thereof, and spring latching means biased outwardly from the guide member to engage the frame, thereby locking the assembly of the frame plunger guide and winding together.

RAY G. OLSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,650,799 Lee Nov. 29, 1927 1,696,615 Trombetta Dec. 25, 1928 1,992,822 Granfleld Feb. 26, 1935 2,252,461 Franz Aug. 12, 1941 2,275,115 Trombetta Mar. 3, 1942 2,305,415 Goff Dec. 15, 1942 2,338,775 Martin Jan. 11, 1944 2,356,377 Bowen Aug. 22, 1944 2,400,344 Frese May 14, 1946 2,419,333 Christiansen Apr. 22, 1947 2,423,869 Blessing July 15, 1947 FOREIGN PATENTS Number Country Date 7,856 Great Britain of 1889 349,203 France May 17, 1905 

